What exactly is rBST on dairy labels?

Published 12:00 am Sunday, July 12, 2020

By Murphy Stafford

N.C. Cooperative Extension

Have you ever picked up a bottle of milk, carton of yogurt, or any other animal-derived dairy product and noticed a little label that says, “rBST Free” or “Milk from cows not treated with rBST”?

If you have, did you pick that product over another just because you thought it was a “safer” or “healthier” option than a product that lacked the label? If yes, what would you do if you found out that there is no significant difference in milk between treated cows and untreated cows and this tiny label is just another marketing ploy? If I have your attention now, let me explain what exactly rBST is.

It is simply the synthetic growth hormone derived from the Bovine Somatotropin made by recombinant DNA technology to create a more pure substance to be injected. Bovine Somatotropin is a species-specific hormone responsible for growth and maintenance during lactation. It directs nutrients straight to the mammary glands and increases lipolysis (break down of fat) and decreases lipogenesis (formation of fat). Eventually, the growth hormone wears off after peak lactation at around 60 days in Holsteins, and body weight will begin to increase naturally.

The purpose of rBST is to increase milk productivity by extending peak lactation and by decreasing the rate of mammary cell lysis. The hormone was approved by the Food and Drug Administration in 1993 under the name Posilac after being tested to make sure there were no ill effects on humans. The drug can be administered in a cow around two months after calving up to the end of lactation. It is injected every 14 days.

A key factor in the reason it has been deemed safe by the FDA is the fact that this hormone is a large protein that will be denatured by the digestive tract if consumed. If absorbed, the hormone is species-specific and could not be used by the human body. At the 2013 annual meeting of the World Health Organization, the group supported the fact that rBST could not be biologically active in humans due to it having species-specific receptors that make it impossible for BST to bind in humans. There has been no clear data that shows a link between health problems in humans caused by the ingestion of milk treated with rBST and there has been no difference of nutrients provided in milk from a treated cow or one not treated.

The main reason that many countries deem rBST not safe is because if proper care is not given to an animal, rBST can cause health issues in the cow. Many U.S. co-ops  do not accept milk from cows treated with rBST.  If the proper feed amount is not given, a cow can become malnourished. But if given proper nutrition and care, the cow will be fine. Many recent studies have shown that using rBST may reduce the environmental cost on a farm  and the cost of production will be lowered due to increased efficiency.

Next time you go out grocery shopping, do a little bit of research into your labels and see if it is worth it to pay more since you might be following along with labels without actually knowing what they mean.

Murphy Stafford is a North Carolina State University summer intern at the N.C. Cooperative Extension.

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